大家好，我又來了~
秀一波最近解BUG學到的東西:WIFI連接和斷鏈。其實本文也不算問題分析，頂多算是問題定位吧？！
目錄
3、熱點未回覆AUTH_RSP或者STA未收到AUTH_RSP
4、熱點未回覆ASSOC_RSP或者STA未收到ASSOC_RSP
1、密碼錯誤導致的連接失敗
其實有的時候並不是用戶真的輸入了錯誤密碼，有可能WIFI底層驅動存在異常。
再者，可以查看一下WIFI配置文件中保存的AP密碼是否與期望值一致。
wpa_supplicant: wlan0: WPA: 4-Way Handshake failed - pre-shared key may be incorrect
wpa_supplicant: wlan0: CTRL-EVENT-SSID-TEMP-DISABLED id=0 ssid="xiaoxiaoxin" aut
2、關聯被拒絕
wpa_supplicant: wlan0: CTRL-EVENT-ASSOC-REJECT status_code=1
wpa_supplicant: wlan0: Request to deauthenticate - bssid=00:00:00:00:00:00 pending_bssid=00:00:00:00:00:00 reason=3 state=ASSOCIATING
wpa_supplicant: wpa_driver_nl80211_disconnect(reason_code=3)
3、熱點未回覆AUTH_RSP或者STA未收到AUTH_RSP
正常情況下，STA發送AUTH request後，會收到一個AUTH_RSP，即正確情況下，內核LOG中會有如下兩行打印，異常情況下，僅有第一行。
這種情況下，可以用其他設備接入AP，看是否存在同樣的問題，則基本判斷出是否爲熱點問題。
4,20619,2759068545,-;AUTH - Send AUTH request seq#1 (Alg=0)...
4,20620,2759170874,-;AUTH - Receive AUTH_RSP seq#2 to me (Alg=0, Status=0)
4、熱點未回覆ASSOC_RSP或者STA未收到ASSOC_RSP
異常情況下，STA端不會有下面的第二行日誌打印。
[ 2854.218696] ASSOC - Send ASSOC request...
[ 2854.238083] PeerAssocRspAction():ASSOC - receive ASSOC_RSP to me (status=0)
5、DHCP FAILURE
四次握手成功但是獲取IP地址失敗：
WifiConfigStore: message=DHCP FAILURE
正常情況下的流程如下：
DhcpClient: Broadcasting DHCPDISCOVER
DhcpClient: Received packet: 10:c7:53:71:ae:7c OFFER, ip /192.168.236.146, mask /255.255.255.0, DNS servers: /192.168.236.1 , gateways [/192.168.236.1] lease time 86400, domain null
DhcpClient: Got pending lease: IP address 192.168.236.146/24 Gateway 192.168.236.1 DNS servers: [ 192.168.236.1 ] Domains DHCP server /192.168.236.1 Vendor info null lease 86400seconds
DhcpClient: Broadcasting DHCPREQUEST ciaddr=0.0.0.0 request=192.168.236.146 serverid=192.168.236.1
DhcpClient: Received packet: 10:c7:53:71:ae:7c ACK: your new IP /192.168.236.146, netmask /255.255.255.0, gateways [/192.168.236.1] DNS servers: /192.168.236.1 , lease time 86400
DhcpClient: Confirmed lease: IP address 192.168.236.146/24 Gateway 192.168.236.1 DNS servers: [ 192.168.236.1 ] Domains DHCP server /192.168.236.1 Vendor info null lease 86400 seconds
6、發送roaming
當前連接AP1信號太弱，此時又掃描到了已連接過的AP2，AP2的信號強度更好，則會斷開AP1，連接AP2，這一系列動作就叫roaming。
如下列中，斷開了與10:0e:0e:20:66:15熱點的連接，連接到了10:0e:0e:20:5e:6d熱點。
wpa_supplicant: nl80211: Associated on 2422 MHz
wpa_supplicant: nl80211: Associated with 10:0e:0e:20:66:15
wpa_supplicant: nl80211: Drv Event 47 (NL80211_CMD_ROAM) received for wlan0
wpa_supplicant: nl80211: Roam event
wpa_supplicant: nl80211: Associated on 2472 MHz
wpa_supplicant: nl80211: Associated with 10:0e:0e:20:5e:6d
7、AP發送了DEAUTH幀導致斷開連接
此時可以連接其他AP測試一下，進而判斷是否是剛纔這個AP的問題
[ 1555.321037] (1)[3319:tx_thread][wlan] Rx Deauth frame from BSSID=[aa:63:df:4c:db:c2]
[ 1555.321093] (1)[3319:tx_thread][wlan] Reason code = 7
目前遇到的問題暫時有這麼幾類，以後再遇到了會再做補充，歡迎一起探討~
相關內容：
WIFI接入之Authentication和Association流程梳理
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